Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755575AbbFQORP (ORCPT ); Wed, 17 Jun 2015 10:17:15 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:35299 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754519AbbFQORH (ORCPT ); Wed, 17 Jun 2015 10:17:07 -0400 Message-ID: <1434550624.23509.18.camel@gmail.com> Subject: Re: [PATCH v2] futex: lower the lock contention on the HB lock during wake up From: Mike Galbraith To: Sebastian Andrzej Siewior Cc: Davidlohr Bueso , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Steven Rostedt , "Paul E. McKenney" , linux-kernel@vger.kernel.org Date: Wed, 17 Jun 2015 16:17:04 +0200 In-Reply-To: <20150617083350.GA2433@linutronix.de> References: <1432056298-18738-1-git-send-email-dave@stgolabs.net> <1432056298-18738-2-git-send-email-dave@stgolabs.net> <20150616192911.GA19500@linutronix.de> <1434484226.1903.19.camel@stgolabs.net> <20150617083350.GA2433@linutronix.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1203 Lines: 25 On Wed, 2015-06-17 at 10:33 +0200, Sebastian Andrzej Siewior wrote: > wake_futex_pi() wakes the task before releasing the hash bucket lock > (HB). The first thing the woken up task usually does is to acquire the > lock which requires the HB lock. On SMP Systems this leads to blocking > on the HB lock which is released by the owner shortly after. > This patch rearranges the unlock path by first releasing the HB lock and > then waking up the task. > > [bigeasy: redo ontop of lockless wake-queues] > Signed-off-by: Thomas Gleixner > Signed-off-by: Sebastian Andrzej Siewior 4.1-rc8-rt4 contains this via 4.0-rt4, and seems fine on my 64 core DL980. I ran a few iterations of futextests and stockfish, then mixed two loops of futextest at different rt prios, with stockfish also rt, and ltplight as tossed in as... crack filler. Box is still doing that, is way too busy, but not griping about it. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/